Knowing how to prevent the flu is essential for maintaining good health and avoiding missed days at work or school. The most effective strategy involves getting an annual trivalent vaccination, which is currently recommended for everyone six months of age and older.
In addition to vaccination, practicing consistent hygiene habits can significantly lower the risk of infection in daily life. Washing hands frequently with soap and avoiding close contact with individuals who are sick are two simple but powerful ways to stop the spread of respiratory germs.
Untreated influenza can lead to severe complications like pneumonia or respiratory failure, especially in high-risk groups such as young children and the elderly. If symptoms like high fever or difficulty breathing appear, a doctor may order a rapid flu test and prescribe antiviral medications to help speed up recovery.
Indications for use
In the United States, the CDC maintains a universal recommendation: the flu shot is recommended for everyone 6 months of age and older, with very rare exceptions.
While everyone should get vaccinated, it is especially critical for populations who are at higher risk of developing serious complications. These groups include:
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Children between 6 months and 5 years of age
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Adults 65 years and older
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Pregnant people (during any trimester) and up to 2 weeks postpartum
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Residents of nursing homes and long-term care facilities
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People with compromised immune systems (e.g., due to HIV, cancer, or immunosuppressive medications)
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People with chronic health conditions, such as diabetes, asthma, heart disease, or chronic kidney disease
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People with certain genetic or neurologic conditions (e.g., Down syndrome, cerebral palsy)
Healthcare personnel and caregivers of vulnerable populations are also advised to vaccinate.
Flu shot types
The flu vaccines available in the US are trivalent.
The trivalent vaccine protects against three strains of the virus: two Influenza A viruses (H1N1 and H3N2) and one Influenza B virus (Victoria lineage). It is available in different formulations, including standard-dose shots, high-dose shots (for seniors), and recombinant or cell-based options.
The tetravalent (four-strain) vaccine is no longer used in the US, as the second Influenza B strain it targeted has not been seen globally since 2020.
When and how to take it
The flu shot schedule is typically as follows:
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Adults: 1 dose, once a year.
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Children 6 months through 8 years old:
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2 doses are required if it is the child's first time getting the flu vaccine, or if they have not received at least 2 total doses in their life before July 1, 2025. These doses should be given at least 4 weeks apart.
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1 dose is required if the child has received 2 or more total doses in previous seasons.
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Children 9 years and older: 1 dose, once a year.
Injection Sites:
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Infants (under 12 months): The vaccine is injected into the anterolateral thigh muscle.
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Children (1 year and older) and Adults: The vaccine is preferred in the deltoid muscle (upper arm) but can be administered in the thigh if necessary.
Possible side effects
The most common side effects of the flu shot are mild and temporary:
1. Headaches and muscle or joint aches
Some people may experience fatigue, body aches, and headaches, which may appear 6 to 12 hours after vaccination.
What to do: Rest and drink plenty of fluids. If the pain is bothersome, you can take analgesics such as acetaminophen (Tylenol) or ibuprofen.
2. Fever, chills, and mild nausea
Some people may feel feverish or have chills. These are usually temporary symptoms that disappear within 1 to 2 days.
What to do: If fever or discomfort is intense, you can take over-the-counter fever reducers as approved by your doctor.
3. Injection site reactions
Soreness, redness, or a small lump at the injection site are common.
What to do: Apply a cold compress to the area. If there is extensive swelling or you cannot move your arm, consult a doctor.
Contraindications for use
The flu shot is contraindicated for:
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Infants younger than 6 months.
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People who have had a severe life-threatening allergic reaction to a previous dose of the flu vaccine or any of its ingredients (except egg).
According to current CDC guidelines, people with egg allergies can safely receive any flu vaccine (egg-based or non-egg-based) appropriate for their age. No special monitoring beyond the standard observation period is required.
People currently experiencing a moderate-to-severe illness with fever should wait until they have recovered before getting vaccinated to avoid confusing disease symptoms with vaccine side effects.
Common questions
1. Does the vaccine protect against H3N2, H1N1, or COVID-19?
The 2025-2026 flu vaccine protects against Influenza A (H1N1 and H3N2) and Influenza B. It does not protect against COVID-19.
2. Do I need to have a flu shot every year?
Yes. Immune protection declines over time, and flu viruses mutate rapidly. The vaccine is updated annually to match the new circulating strains.
3. When can I get my flu shot?
September and October are generally the best times to be vaccinated. Ideally, everyone should be vaccinated by the end of October.
4. Can I get the flu and COVID-19 vaccines together?
Yes. The CDC confirms that you can get a flu vaccine and a COVID-19 vaccine at the same visit.
5. Can pregnant people get a flu shot?
Yes. Pregnant people are at higher risk of severe illness from the flu. The vaccine helps protect the pregnant person during pregnancy and passes antibodies to the baby, protecting them for several months after birth.